1. Field of the Invention
The present invention generally relates to techniques for proactive fault-monitoring in computer systems. More specifically, the present invention relates to a method and an apparatus that proactively detects metal whisker growth in a computer system by monitoring and analyzing real-time electromagnetic interference (EMI) signals from the computer system.
2. Related Art
The European Union's directives on Waste Electrical and Electronic Equipment (WEEE) and the Restriction of Hazardous Substances (RoHS), as well as the California State Senate bill on electronic waste recycling, have been enacted to protect the environment from “electronic waste.” One of the materials required to be eliminated from electronic products under these new laws is lead. Lead (Pb) is the main substance in the Sn—Pb alloy which has been widely used as a plating material for printed circuit boards and wires to improve and preserve solderability over long periods of storage. As a result, electronic components are now being plated with pure tin (Sn) or high tin alloys as an alternative to the Sn—Pb plating.
However, a disadvantage of using pure tin or high tin alloy as a plating material is the spontaneous growth of needle-like conductive tin crystals from tin finished surfaces. These needle-like structures are commonly referred to as “tin whiskers.” Note that tin whisker formation and growth can potentially cause current leakage or electrical shorting between adjacent leads of a component, between leads of adjacent components on a circuit board, or between leads of a component and the traces on the circuit board.
Although pure tin or high tin alloy-based products are relatively new in the electronics industry, a number of catastrophic failure events due to tin whisker related electrical shorting have already been reported in military, avionics, telecommunication, medical and consumer electronics applications. For example, Boeing reported the failure of a space control processor due to tin whiskers, which resulted in the complete loss of a $200 million communication satellite. More recently, there was a well-publicized failure of electronic systems on NASA's Space Shuttle due to long tin whisker formation.
One technique for detecting tin whisker buildup is to have trained personnel visually inspecting electronic parts that are mostly likely to grow tin whiskers. However, visual inspection is extremely labor-intensive and requires complex systems to be disassembled and reassembled. Hence, it is impractical to perform routine visual inspections for tin whiskers inside a large number of electronic systems. Another technique that the electronics industry is adopting to mitigate tin whisker growth is to apply conformal coatings on the electronics. However, the needle-like tin whiskers can still poke through a conformal coating. Unfortunately, there is no known technique in the electronics industry capable of proactively monitoring and detecting the buildup of conductive whiskers before shorting failures occur.
Hence, what is needed is a method and an apparatus that facilitates proactively detecting the incipience or the onset of conductive whiskers without the above-described problems.